Doesn't xdrive (or 4wd per say) gives more grip and anti-slip capabilities to a car?

Like when driving on slippery wet roads, steep cornering, et al ?

You don't get more grip from having AWD, but you distribute the forward traction forces over several tires. This makes the car more stable, also in corners. The maximum cornering speed will still be the same.

When driving around ice tracks, you notice the AWD advantage mostly during acceleration out of tight corners. You can get a lot more power down.

The extra weight up front is a disadvantage at corner entry, so RWD cars can usually brake slightly later than the AWD version.